1. Field of the Invention
The present invention relates generally to sense amplifiers for memory systems or other small signal or analog circuits, and more particularly to a sense amplifier including a preamplifier circuit including cross-coupled charge transfer circuits
2. Description of the Prior Art
In the recent past there have been several improvements in sensing circuits for memory cells, particularly the one device memory cell. One significant concept for improving the sensitivity of sensing circuits is the concept of charge transfer as described in U.S. Pat. No. 3,764,906, entitled "Stored Charge Detection by Charge Transfer", issued Oct. 10, 1973, to L. G. Heller and assigned to the International Business Machines Corporation. Other references related to this concept are U.S. Pat. No. 3,760,381, entitled "Stored Charge Memory Detection Circuit" issued Sept. 18, 1973, to Y. L. Yao and assigned to the International Business Machines Corporation; U.S. Pat. No. 3,789,312, entitled "Threshold Independent Linear Amplifier" issued Jan. 29, 1974 to L. G. Heller et al and assigned to the International Business Machines Corporation; U.S. Pat. No. 3,774,176, entitled "Semiconductor Memory Having Single Transistor Storage Elements and a Flip-Flop Circuit for the Evaluation and Regeneration of Information," issued Nov. 20, 1973 to K. U. Stein et al and assigned to Siemens Aktiengesellschaft; and U.S. patent application, Ser. No. 491,023, entitled "Differential Charge Transfer Sense Amplifier", filed July 23, 1974, by R. H. Dennard et al and assigned to the International Business Machines Corporation; and a paper entitled "High Sensitivity Charge-Transfer Sense Amplifier", 1975 IEEE International Solid-State Circuits Conference Digest, pp. 112-113, by L. G. Heller et al.
Another improvement in sensing circuits is the dynamic latch circuit and the threshold independent dynamic latch as described in U.S. patent application Ser. No. 591,983, entitled "Threshold Independent Latch", filed June 30, 1975, by D. P. Spampinato and assigned to the International Business Machines Corporation.
The present invention is a further improvement in the art of memory sensing circuits by embodying the novel concept of cross-coupled charge transfer to provide higher performance and greater sensitivity than is possible with the described prior art technology.